The knee joint is frequently the object of injury and is often repaired using arthroscopic surgical procedures. Common repairs to the knee joint include repair and reconstruction of damaged anterior cruciate ligaments (ACL) and posterior cruciate ligaments (PCL). When the ACL or the PCL have ruptured and are non-repairable, they may be independently replaced as needed and the knee reconstructed through the use of ligament grafts. The PCL may alternatively or additionally be replaced. The ACL and the PCL are three-dimensional structures with broad attachments and a continuum of fibers. These fibers are of different lengths, have different attachment sites, and are under different tensions.
To provide proper repair of the cruciate ligament defect, the ligament graft must be implanted into the defect site with the proper laxity. If there is too much relaxation in the ligament graft, hyperextension of the knee joint may result. If there is insufficient laxity in the ligament graft, the graft will be tight and the patient may not achieve the desired range of motion in the knee.
Current techniques of providing the ligament graft to the defect site include stretching the ligament graft while the graft is being soaked in a saline solution. Shortcomings of this technique are that the saline solution can cause unpredictability in the final size of the graft due to shrinkage of the graft and that the saline bath and the stretching of the graft may happen too remotely from the surgical table thereby causing the graft to become misshapen prior to implantation. Other techniques include stretching the graft and then storing the graft in a trough of a warm solution until the surgeon is ready to implant the graft.
These and other current techniques facilitate changes in graft size during graft preparation and implantation. In some instances, between tensioning the graft and transferring the graft to a warming source, the graft can change size multiple times. This is not desirable because upon implanting the graft, there may be additional relaxation of the graft due to in vivo conditions. If the graft is not prepared and maintained in a manner where the predictability of the graft size in vivo is known or can be controlled, the graft will additionally relax after implantation thereby causing hyperextension of the knee.
Accordingly, there is a need for improved methods for preparing ligament grafts. There is also a need for surgical methods which allow for control of the graft size prior to implantation and upon implanting into the defect site.